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Biomedical subjects

J D Maloney

Publications and source records attributed to J D Maloney.

At least 19 recordsLinked to original sources
PubMed1992

Catheter ablation of the atrioventricular junction using radiofrequency energy and a bilateral cardiac approach.

Radiofrequency current catheter ablation was used successfully to create complete atrioventricular (AV) block in 60 of 61 patients (98%) with drug refractory supraventricular tachyarrhythmias. The remaining patient developed Mobitz I AV block and is clinically improved (clinical efficacy 100%). In 54 patients (89%), complete AV block was achieved using a right-sided approach. Patients aged > 60 years needed significantly fewer right-sided radiofrequency applications to produce complete AV block (5.3 +/- 5.3 vs 11.1 +/- 10.0; p = 0.009). In 6 of 7 patients with unsuccessful right-sided ablation, a left ventricular approach was used. In each case, 1 to 4 additional radiofrequency applications produced complete AV block. Patients with unsuccessful right-sided ablation were generally younger than those with successful ablation (50 +/- 16 vs 64 +/- 11; p = 0.007). It is concluded that catheter ablation using radiofrequency current is an extremely effective means of producing complete AV block. Older patients appear to be more susceptible to right-sided radiofrequency approaches. Left ventricular ablation easily produces complete AV block in patients refractory to right-sided attempts.

Adult↗
PubMed1992

Flecainide therapy in patients treated for supraventricular tachycardia with near normal left ventricular function.

Concerns about the safety and efficacy of class IC antiarrhythmic agents have arisen as a result of the recent CAST data. We reviewed records of 175 consecutive patients treated with flecainide between July 1, 1988 and July 5, 1989. One hundred ten patients with normal or mildly impaired left ventricular function and symptomatic supraventricular arrhythmias were identified. Follow-up data were obtained on 102 patients for a mean of 14 months. The average duration of flecainide therapy was 13 months. Tachyarrhythmias treated included atrial fibrillation/flutter, atrioventricular reentry, and atrioventricular nodal reentry. Flecainide provided effective antiarrhythmic therapy in 62% of the patients and was discontinued in 38% of the patients. Left atrial size did not predict treatment failure. Two patients developed proarrhythmic events (nonsustained ventricular tachycardia). There were no deaths during the follow-up period. In conclusion, flecainide provides safe and effective therapy for supraventricular tachyarrhythmias in patients with normal or mildly impaired left ventricular function.

Atrial Fibrillation↗
PubMed1992

Analysis of deaths in patients with an implantable cardioverter defibrillator.

The cause of death and clinical characteristics of 26 patients that died after implantable cardioverter defibrillator placement were reviewed and compared to the 145 patients still living after a mean follow-up of 17 months. Operative mortality was 4% (7/171) and resulted from postoperative ventricular arrhythmias (four patients), heart failure (two patients), and respiratory failure (one patient). Operative mortality was significantly higher (1.7% vs 9.6%, P less than 0.05) following concomitant surgical procedures. Total late mortality was 11% (18/171). Thirteen deaths (75%) occurred in-hospital from progressive deterioration of left ventricular function (nine patients), arrhythmia (two patients), and noncardiac causes (two patients). Outpatient mortality was 3.5% (6/171) and resulted from presumed sudden cardiac death in five of six patients; two of the five had devices that were inactive, one had high defibrillation thresholds, and two had suspected bradyarrhythmic deaths. One postoperative death and one late in-hospital death were also considered sudden cardiac deaths for a total of seven patients with defibrillation system failures. By multivariant analysis, preoperative clinical characteristics associated with a worse prognosis following defibrillator implantation were identified: presentation as ventricular tachycardia (P less than 0.02), induction of sustained monomorphic ventricular tachycardia (P less than 0.05), poor left ventricular performance (P less than 0.01), poor functional status (P less than 0.001), and the use of diuretics (P less than 0.01). Frequent device discharges (P less than 0.001) and concomitant antitachycardia pacing systems (P less than 0.001) were markers for greater arrhythmia recurrence and were potent predictors of a worse prognosis and particularly sudden death.

Arrhythmias, Cardiac↗
PubMed1992

Pacing lead survival: performance of different models.

UNLABELLED: Recent reports have shown poor survival of some leads currently in use. Long-term survival analysis of 2,444 leads (1,059 atrial and 1,385 ventricular) implanted in this institution since January 1980, and having at least 1 month of follow-up was performed. The survival of 123 different models was compared with the average survival of all the leads implanted in the corresponding chamber. Failure was defined as inactivation of the lead (electrical abandonment, explant, or cap) due to insulator and/or conductor fracture. RESULTS: The mean follow-up was 33 +/- 32 months. The cumulative survival for different atrial lead models was consistent with the average performance in the atrium. No atrial lead showed better or worse survival compared to the others. In the ventricular group, the Medtronic 4012 lead showed statistically significant poorer survival (P = 0.01) compared with the average survival of the ventricular leads. The Cardiac Pacemakers, Inc. (CPI) 4010 lead showed a nonsignificant (P = 0.12) worse performance than the average for ventricular leads. CONCLUSIONS: (1) The Medtronic 4012 had a significantly poorer performance than the rest of the leads. A trend in similar direction was found for the CPI 4010, also in the ventricular group; (2) Atrial lead models showed a stable survival; and (3) Frequent follow-up is required for some leads, especially in pacemaker dependent patients.

Actuarial Analysis↗
PubMed1992

Incidence and predictors of loss of pacing in the atrium in patients with sick sinus syndrome.

Atrial and dual-chamber pacemakers may be associated with reduced morbidity in patients with the sick sinus syndrome (SSS). In some patients, however, subsequent development of chronic atrial fibrillation or atrial lead failure make long-term pacing in the atrium not feasible. We analyzed the incidence and predictors of loss of atrial pacing in 395 consecutive patients with SSS (376 with dual-chamber pacemakers and 19 with single-chamber atrial pacemakers). None of them was in established atrial fibrillation at time of implant. Patients were followed-up for 55 +/- 35 months. Actuarial survival of effective atrial pacing was 92.5% at 1 year, 85% at 5 years, and 76.5% at 10 years. Overall, 60 patients lost atrial pacing. The most frequent cause was the development of chronic atrial fibrillation (53 patients). By multivariate analysis (Cox proportional-hazards model), independent predictors of loss of pacing in the atrium were preimplant episodes of paroxysmal atrial fibrillation (PAF) lasting more than 1 hour (P < 0.001; hazard ratio (HR) = 4.3); prior history of PAF for more than 5 years (P < 0.001; HR = 2.67; and endocardial P wave < 2 mV (P = 0.014; HR = 1.96). In a subgroup of patients (n = 187) who had echocardiograms, a left atrium > 50 mm was also an independent predictor of loss of atrial pacing (P = 0.028; HR = 2.28).(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1992

Incidence and predictors of syncope in paced patients with sick sinus syndrome.

UNLABELLED: In spite of a normal pacemaker function, syncope still occurs in some patients with sick sinus syndrome (SSS). Causes often remain unknown. To identify predictors and etiologies of this bothersome symptom, we studied 507 patients who received atrial, ventricular, and dual-chamber pacemakers for SSS. During a mean follow-up of 62 +/- 38 months, actuarial incidence of syncope was 3% at 1 year, 8% at 5 years, and 13% at 10 years. Causes were vasovagal (18%), orthostatic hypotension (25.5%), rapid atrial tachyarrhythmias (11.5%), ventricular tachycardia (5%), acute myocardial ischemia (2.5%), and pacemaker/lead malfunction (6.5%). In 13 patients (29.5%), syncope remained unexplained. The only preimplant predictor for syncope was syncope as primary indication for pacemaker implant. Electrocardiographic correlation with bradycardia was not a predictor of relief of syncope during the follow-up. IN CONCLUSION: (1) syncope in paced patients with SSS has multiple etiologies and may be multifactorial; (2) the only predictor of syncope after pacemaker implant is the occurrence of preimplant syncope as the main indication for pacing; (3) extensive Holter monitoring is not useful to document bradycardiac origin of syncope nor to predict its recurrence; (4) SSS probably overlaps with other entities such as autonomic dysfunction, vasovagal syncope, carotid sinus hypersensitivity, and venous pooling, which would provide an explanation for recurrent syncope in patients with normal pacemaker function.

Actuarial Analysis↗
PubMed1992

Survival after a first episode of ventricular tachycardia or fibrillation.

Recent outcome analyses in ventricular tachycardia (VT) and ventricular fibrillation (VF) have included patients undergoing electrophysiological study (EPS) at tertiary care centers. The selection process involved could introduce bias in the reported populations. We analyzed the outcome of 42 consecutive patients (aged 63 +/- 11 years) admitted to a coronary care unit within 48 hours of a first episode of VT/VF not associated with reversible causes. All patients recovered neurologically and were candidates for EPS. Nine patients (21%) died during the initial hospitalization (none had EPS), and another nine died during a follow-up of 17 +/- 12 months. Actuarial survival at 1 and 2 years was 64% and 62%, respectively. By Cox's model, congestive heart failure functional Class III-IV (P = 0.008; hazard ratio = 3.7) was the only independent prognostic factor. Among patients discharged, subsequent survival did not depend on the performance of EPS or on the antiarrhythmic therapeutic modalities used. Mortality after a first episode of VT/VF is high. Severe congestive heart failure is the most powerful prognostic factor. Studies including successfully referred patients undergoing EPS may not reflect the true natural history of patients with VT/VF.

Actuarial Analysis↗
PubMed1992

Physiology of rate-responsive pacing.

The search for a pacemaker that accurately and easily mimics normal physiology is a continuing effort. There have been many achievements in the past, including sensing of the pacing chamber and programming of the pacing rate, sensitivity, and output. Present pacing developments include atrioventricular synchrony and rate adaptiveness. Results of studies on activation sequence and circadian variations will impact future pacing. The usefulness, cost effectiveness, and clinical value of some of the new pacing features remain unclear. Further clinical trials are necessary to clarify the value of new pacing techniques.

Adams-Stokes Syndrome↗
PubMed1991

Patients with a high defibrillation threshold: clinical characteristics, management, and outcome.

Of 125 patients prepared to receive implantable cardioverter-defibrillators (ICDs) with the patch-patch configuration of the difibrillating electrodes, 23 (18%) had high (greater than or equal to 25 joules) defibrillation thresholds (DFTs). These patients had lower left ventricular ejection fractions (27 +/- 12 vs 34 +/- 13; p less than 0.03) and a higher incidence of previous heart surgery (47% vs 19%; p less than 0.01) than patients with normal DFTs but did not differ in age, type of heart disease, incidence of concomitant heart surgery, or use of antiarrhythmic medication. Defibrillators were implanted in 18 of these 23 patients, 12 during the initial surgery and six after repeat DFT testing 2 weeks later. After 22 +/- 11 months of follow-up, four patients with ICDs died (two suddenly, and two of nonsudden cardiac causes). Two patients without ICDs died of nonsudden cardiac causes. Appropriate shocks were received by five patients (29%) including both who died suddenly later. A high DFT may be more common than previously stated. It is associated with poor ventricular function and previous heart surgery. Repeated DFT testing may be useful in some patients. A high DFT does not preclude successful ICD shocks, but other therapies may provide better results.

Aged↗
PubMed1991

DDIR versus VVIR pacing in patients with paroxysmal atrial tachyarrhythmias.

Patients with sinus node dysfunction (SND) in particular those with tachycardia-bradycardia syndrome and patients undergoing atrioventricular nodal ablation procedures for refractory paroxysmal atrial tachyarrhythmias (PAT), are candidates for single chamber (VVIR mode) or dual chamber rate responsive (DDIR mode) systems. To evaluate the benefits and disadvantages of each pacing mode we retrospectively analyzed 33 patients with a history of frequent PAT who received a VVIR (22 patients); or a DDDR pacemaker (11 patients) programmed to the DDIR mode. The mean follow-up time was 25 and 18 months, respectively. Preimplant left atrial diameter was significantly smaller in the DDIR group. Chronic atrial fibrillation developed in 54% of the VVIR patients and 27% of the DDIR group, but this difference was not significant. Complications of patients with VVIR pacemakers included new mitral and tricuspid insufficiency, stroke, pacemaker intolerance and aggravated congestive heart failure. Patients with DDIR pacemakers had a lower incidence of symptoms and complications. However, this group received more antiarrhythmic medication, required a closer follow-up, and their pacemakers needed frequent reprogramming. Our findings suggest that VVIR is a poor choice for patients with SND, congestive heart failure, and PAT, and that DDIR may be an acceptable alternative.

Anti-Arrhythmia Agents↗
PubMed1991

Early clinical experience with a minute ventilation sensor DDDR pacemaker.

UNLABELLED: The new DDDR pacemaker META DDDR utilizes a minute ventilation sensor based on transthoracic impedance measurements. The sensor determines the metabolic indicated interval, the atrioventricular (AV) delay and the postventricular atrial refractory period (PVARP). The baseline PVARP must be carefully selected to define nonphysiological tachycardias. If a P wave falls within the PVARP the pacemaker will automatically switch to the VVIR mode. This behavior prevents tracking of paroxysmal atrial tachyarrhythmias (PAT). Twenty-eight patients with sinus node dysfunction (n = 20), AV junction ablation (n = 5), complete or intermittent AV block (n = 3); who received a META DDDR pacemaker were studied. The mean age was 65 +/- 13 years. RESULTS: mode switching (reversion) to VVIR was observed in 57% of the patients. Forty-two percent had episodes of mode switching to VVIR during a stress test, four related to PAT, and seven to sinus tachycardia. Fifty percent had episodes of mode switching to VVIR during a 24-hour Holter, four related to PAT, three to retrograde P wave sensing, and two to sinus tachycardia. At the last follow-up, 20 of the 26 patients initially programmed to the DDDR mode remained in the DDDR mode, while five were reprogrammed to the DDD and one to the VVIR mode. Mode switching has a high sensitivity but a low specificity for PAT. It appears to be a useful approach to prevent rapid tracking of atrial tachyarrhythmias. Careful PVARP programming is critical to appropriate reversion behavior, but further modifications of the algorithm are needed to improve its performance.

Aged↗
PubMed1991

Implantable cardioverter defibrillator implanted by nonthoracotomy approach: initial clinical experience with the redesigned transvenous lead system.

Standard implantation procedure for the implantable cardioverter defibrillator (ICD) has traditionally required a thoracotomy approach. A newly revised nonthoracotomy defibrillator lead system that uses a single transvenous tripolar endocardial lead alone or in combination with a subcutaneous/submuscular patch lead was introduced into clinical trials in September, 1990. Fourteen patients requiring a cardioverter defibrillator for recurrent sustained ventricular tachycardia (eight patients) or aborted sudden cardiac death (six patients) were evaluated for implantation of this lead system. Primary successful lead system implantation was obtained in nine patients. The remaining five patients had unacceptably high defibrillation thresholds (DFTs) for implantation. One of the nine initially successful implants demonstrated unacceptable DFTs and cross-talk inhibition from a permanent pacemaker necessitating removal of the nonthoracotomy lead system and replacement with a conventional lead system via thoracotomy. All remaining primary implanted patients experienced successful conversion of induced ventricular fibrillation prior to hospital discharge. Continued follow-up and greater experience to confirm the durability and efficacy of the nonthoracotomy AICD lead system are needed.

Aged↗
PubMed1991

Retrospective analysis of patients undergoing one- or two-stage strategies for myocardial revascularization and implantable cardioverter defibrillator implantation.

Internal defibrillation leads were placed at time of coronary revascularization in 79 patients. In 34, an implantable cardioverter defibrillator (ICD) was placed simultaneously (group I). A two-stage strategy (selective implantation of the ICD in patients with postoperative spontaneous or inducible ventricular tachycardia [VT]) was followed in 45 patients (group II). Group I patients had failed more antiarrhythmic drug trials (2.9 +/- 1.6 vs 1.5 +/- 1.6; P = 0.02), including amiodarone (62% vs 20%; P less than 0.001). There were four operative deaths in each group. Postoperatively, VT was present in 27 group II patients (60%), 25 of whom received an ICD (two refused device implantation). Patients with postoperative VT had a lower left ventricular ejection fraction than those without VT (33 +/- 9 vs 47 +/- 16; P = 0.01). Actuarial survival at 1, 2, and 3 years was 88 +/- 6, 88 +/- 7, and 88 +/- 10 in group I; and 83 +/- 6, 76 +/- 7, and 76 +/- 11 in group II (NS). No patient without an ICD (based on the postoperative electrophysiological study [EPS]) died suddenly. Five patients (6%) had ICD system infection. Sudden death was largely prevented by either strategy, but relatively high rates of operative mortality and ICD system infection were observed. Prospective studies should identify patients more likely to benefit from one or another strategy.

Aged↗
PubMed1991

Safety of external cardioversion/defibrillation in patients with internal defibrillation patches and no device.

Placement of prophylactic epicardial defibrillation patches at time of open-heart surgery in patients at risk for postoperative arrhythmias has been strongly questioned. Concern has centered on the ability to safely perform subsequent external defibrillation if needed. From 61 patients who were treated with a two-stage strategy we identified 17 who, while wearing epicardial patches and no generator, received external cardioversion/defibrillation for 20 episodes of hemodynamically unstable ventricular arrhythmias. All the patients had one small and one large patch. Eighteen of the episodes were induced during electrophysiological testing (with transthoracic shocks delivered via pad electrodes oriented in an apex-posterior configuration) and two were spontaneous. The episodes occurred at 21 +/- 27 days from patch implant. Thirteen episodes (65%) were converted with one shock at an energy level of 185 +/- 65 J. Seven (35%) required a second shock at 351 +/- 22 J. The accumulated energy requirement was 286 +/- 205 J. No adverse outcomes were noted. The number of episodes requiring more than one shock and the energy requirements were not different from those in a control group of 20 similar arrhythmias treated with the same equipment. Under these conditions, external cardioversion/defibrillation in patients with one large and one small epicardial defibrillation patch was uniformly successful. Further data is needed in the out-of-hospital setting and on the results of external defibrillation in patients with two large patches.

Adult↗
PubMed1990

Chronic transvenous pacemaker lead removal using a unique, sequential transvenous system.

Transvenous removal of 43 consecutive chronic pacemaker leads was successful in 28 patients. For leads not removed by traction at the pacemaker connection terminal, a unique locking stylet was advanced through the inner coil lumen and engaged at the tip to allow traction without lead elongation. Leads not extracted with the locking stylet alone had traction maintained on the stylet as sheaths were advanced over the lead to dilate and detach any fibrous tissue adherent to the lead. By applying traction at the pacemaker connection terminal, 2 leads were removed. The locking stylet alone extracted 9 leads. Both the locking stylet and sheaths were necessary to explant 32 leads. There were 15 right atrial and 22 right ventricular leads completely removed. Additionally, 6 right ventricular leads were subtotally removed leaving only the tip in the right ventricular apex. Avulsed myocardium was removed with the lead in 1 patient without sequelae. A subacute hemothorax developed in 1 patient 18 days after discharge requiring drainage, and subclavian vein thrombosis developed in another, which was successfully treated with anticoagulation. Hypotension occurred in 1 patient during final positioning of new leads, which responded to conservative treatment. Chronic pacemaker leads can be reliably removed without thoracotomy. Both a unique locking stylet to allow traction without lead elongation and a sheath to dilate and detach adherent fibrous tissue are needed for consistent success. Recognized complications included myocardial avulsion without sequelae, subacute hemothorax, subclavian vein thrombosis and transient hypotension.

Adult↗
PubMed1990

Vasovagal syncope: diagnostic role of head-up tilt test in patients with positive ocular compression test.

We investigated the relative merits of the ocular compression test and the head-up tilt test to aid differentiation of syncope and seizures in young patients. Sixteen patients (10 males and 6 females) with a mean age of 14 +/- 4.7 (SD) years (range 7-22 years) underwent graded head-up tilt (15 degrees, 30 degrees, and 45 degrees for 2 minutes each, then 60 degrees for 20 minutes) following positive ocular compression testing defined as precipitation of asystole for at least 3 seconds (mean 5 seconds +/- 2 seconds, range 3-12 seconds). Each patient presented with recurrent unexplained loss of consciousness (mean number of episodes 30 +/- 45, mean duration of illness 52 +/- 40 months), and seven patients were receiving anticonvulsant medications, three of these had normal EEGs. Eleven patients (69%) developed vasovagal syncope during head-up tilt, reproducing their clinical episodes (systolic blood pressure decreased from 105 +/- 10 mmHg to 84 +/- 13 mmHg, diastolic blood pressure from 75 +/- 9 to 22 +/- 25 mmHg, and heart rate from 89 +/- 13 beats/min to 37 +/- 20 beats/min). Asystole occurred in two patients during vasovagal syncope lasting 11 seconds in one and 16 seconds in the other, and, it was associated with myoclonic movements in both (convulsive syncope). Based on these findings, and given the perceived potential hazards of the ocular compression test, the head-up tilt test may be a safer procedure that adds useful information to the diagnostic evaluation of these patients.

Adolescent↗